CPR G5C Class 1246 Pacific

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Berkman
Posts: 25
Joined: Wed Aug 16, 2017 7:55 pm

Re: CPR G5C Class 1246 Pacific

Post by Berkman » Sun Nov 19, 2017 1:27 pm

That seems like a nightmare building a cylinder block that way. Save yourself a year of design/build work and years of frustration with getting it to seal and buy a cylinder block from Little Engines. Would be worth every penny...

thunderskunk
Posts: 23
Joined: Mon Jul 31, 2017 8:24 pm
Location: Vermont

Re: CPR G5C Class 1246 Pacific

Post by thunderskunk » Mon Nov 20, 2017 10:49 pm

Berkman wrote:That seems like a nightmare building a cylinder block that way. Save yourself a year of design/build work and years of frustration with getting it to seal and buy a cylinder block from Little Engines. Would be worth every penny...
You're right. I backtracked a little bit, and I did take a second look into the little engine's castings as well. I could probably make their light northern parts work, but the price isn't right. I think I've got what I need in the scrap pile anyways. I tried copying a welded cylinder block design I saw in Nelson's book there, shown in the attached photo. I'm not an amazing welder, but this seems achievable with a lot of modification to what's shown here. Worst case, I get practice welding and save up for the castings anyways.

I know CAD isn't the favorite method for drafting around these parts, but that's what they teach now. As an aside, it's actually pretty messed up how little they teach about dimensions and tolerancing in school. My boss lent me ASME Y14.5M, which we should have had in class from day one. On the bright side, that CAD stuff is pretty nifty. I found out through parts not matching that the erection drawing I have has a 1/2" vertical offset between the cylinder and driver center lines, and that the positions shown are not exactly halfway between TDC and BDC. Those two errors alone would have added up to 3/4 inch of rod length where I wouldn't want rod length.
start of rods and different saddle.jpg
"We'll cross that bridge once we realize nobody ever built one."

thunderskunk
Posts: 23
Joined: Mon Jul 31, 2017 8:24 pm
Location: Vermont

Re: CPR G5C Class 1246 Pacific

Post by thunderskunk » Wed Jan 03, 2018 11:40 pm

Hey,

Just a quick update. I think I've got the majority of the linkages figured out. I have a lot of playing to do with the saddle and cylinder block in general, but I've seen a welded-up cylinder set before so I think it'll work. Once I have the channels drawn up for steam passages I can verify the linkages are all in the right spots, then I'll feel comfortable cutting up the frame. Worst case, I cut everything but the saddle mount

Some calculations from Machinery's Handbooks says my little press idea for wheels is impossible for what I want to do. Lots of silly number crunching, and it was a whole lot of fun, learned a lot, but a waste of time otherwise. Just picked up a rotary table from work, so I can do my own patterns no problem.

All said and done, the boiler barrel shown is a draft, and by the looks of it.... yea I'm thinkin about faking the 9 inch section as well. DOM tube is way too expensive so I can get a tiny bit more steam head. Lots to think about, but a few years out anyways. Took me a bit, but I found out the right side leads. I just spotted that nifty little bolt-in counterweight on the middle driver (anybody know what that's called?) which meant the 90 degree offset had to go in one specific direction.
Attachments
drawings status 20180103.png
"We'll cross that bridge once we realize nobody ever built one."

Mountaineer
Posts: 114
Joined: Sun Dec 02, 2007 4:45 pm
Location: Canada

Re: CPR G5C Class 1246 Pacific

Post by Mountaineer » Thu Jan 04, 2018 6:08 am

Carr's Machining in Vancouver BC has a cast iron cylinder block for CPR locos. Only slightly larger than scale for a G5 but would suggest using someone's casting and not going down the route of fabricating. Esp as a beginner.

Mountaineer.

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NP317
Posts: 920
Joined: Tue Jun 24, 2014 2:57 pm
Location: Northern Oregon

Re: CPR G5C Class 1246 Pacific

Post by NP317 » Thu Jan 04, 2018 11:30 am

"Took me a bit, but I found out the right side leads."

Most locomotive builders had the right side cylinder lead.
However, the Pennsylvania RR designs had left hand lead! (?All of them?)
I bet Charles Wooten, one of their major early designers, was left handed...
~RN

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makinsmoke
Posts: 1729
Joined: Thu Jul 10, 2003 12:56 pm
Location: Texas Hill Country

Re: CPR G5C Class 1246 Pacific

Post by makinsmoke » Sat Jan 06, 2018 9:52 am

And they ran their geeps backwards.....

:lol:

thunderskunk
Posts: 23
Joined: Mon Jul 31, 2017 8:24 pm
Location: Vermont

Re: CPR G5C Class 1246 Pacific

Post by thunderskunk » Sat Jan 06, 2018 5:40 pm

makinsmoke wrote:And they ran their geeps backwards.....

:lol:
I did the inspection on a GP9 replacing check valves and control stand parts (1272 day? it's been a while) where they'd manufactured the engine to go backwards because of one union's demands, then was sold to another railroad where the requirement was the opposite, so it was a backwards-facing cab refitted to face forward. That was a mess...
"We'll cross that bridge once we realize nobody ever built one."

Pontiacguy1
Posts: 714
Joined: Thu Apr 26, 2012 10:15 am
Location: Tennessee, USA

Re: CPR G5C Class 1246 Pacific

Post by Pontiacguy1 » Sun Jan 07, 2018 4:15 pm

The Southern also ran their Geeps long-nose to the front. They said it was to protect their crew in case of a crash.

thunderskunk
Posts: 23
Joined: Mon Jul 31, 2017 8:24 pm
Location: Vermont

Re: CPR G5C Class 1246 Pacific

Post by thunderskunk » Mon Jan 08, 2018 10:29 pm

Last CAD update, I swear.

My 'assembly' of the linkages is finish, which means I now have a moving projection. Like, it moves. I'm pretty happy with it.

I have lots of number crunching to do now. My slots in the valve liner are in the wrong spots, and something is causing the reverser in center to still admit steam into the cylinders. I might do the spring rigging as well, but I have those drawings and they're pretty straight forward.

Might make a model of one side in 3/4" scale to play with the possibility of fabricating the cylinder block. If I find that impossible, I'll go the route of finding a casting, I promise.
Attachments
linkage assembly complete 20180108.png
"We'll cross that bridge once we realize nobody ever built one."

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